The Role of Brachytherapy in Treatment of Oral Tongue Cancer

Abstract

Brachytherapy (BT) is a useful modality in both the definitive and adjuvant treatment of oral tongue cancer either as stand-alone treatment or in combination with external beam radiation therapy (EBRT), surgery, and/or chemotherapy whether in the primary or recurrent setting. It can be used as a boost treatment to deintensify the dose of EBRT, as a definitive treatment option alternative to surgical management, and as a stand-alone adjuvant therapy in patients with positive surgical margins. We review our 10-year experience. Between January 2004 and December 2014, 39 patients (pts) with oral tongue cancer received Ir-192 LDR BT as part of their treatment course. Pt characteristics were as follows: median age of 53 years (range 20-88); 27 males, 12 females; T stage: 20 T1, 15 T2, 1 T3, 2 T4, 1 multifocal; N stage: 26 N0, 4 N1, 4 N2, 5 Nx; 31 newly diagnosed (18 T1, 10 T2, 1 T3, and 2 T4); and 8 recurrent (3 T1, 4 T2, and 1 multifocal). The combination of EBRT and BT was prescribed for 20 pts, and 19 pts received BT alone. Eight pts were treated definitively with EBRT+BT (n=6; T2N0, multifocal primary, T2N2b, T3N0, T4N1, T4N2c) or with BT and neck dissection (n=2, both T2N0). Thirty-one were treated adjuvantly with EBRT+BT (n=14) or with BT alone (n=17). Indications for EBRT were elective nodal RT (n=3), LN+ (n=3), PNI (n=7), and recurrence (n=1). In the pts receiving adjuvant BT only, indications for BT were close/positive margin (n=11), PNI (n=2), or both close/positive margin+PNI (n=4). Four of 17 adjuvant BT only pts did not have elective node dissection (LND), while 13 did have LND. The median EBRT dose was 54 Gy (30.6-70 Gy), and 1 pt received protons. The median BT dose in the EBRT+BT group was 20 Gy (10-27 Gy). The median BT dose in the BT alone group was 45 Gy (30-60 Gy). The median number of catheters used was 4 (2-12). Tracheostomy was performed in the majority of pts, and 8 pts also had neck dissection at the time of BT catheter placement. Nine pts in the EBRT+BT group received systemic therapy. For the entire cohort, the median follow-up is 40.5 months (7-118 months). The 3-year local control (LC), regional control (RC), and overall survival (OS) is 88%, 75.4%, and 83%, respectively. Among the definitively treated pts, 3-year LC, RC, and OS is 100%, 85.7%, and 60%, respectively. Among the 14 treated with adjuvant EBRT+BT, the 3-year LC, RC, and OS is 91.7%, 78.8%, and 100%, respectively. Among the 17 pts receiving adjuvant BT alone, 3-year LC, RC, and OS is 82%, 67.3%, and 84.6%, respectively. Among this subset, LND impacted on regional control (3-year RC 84% vs 25%, P=.017) Oral tongue BT offers the potential for highly individualized treatment in multiple clinical scenarios. It offers highly conformal therapy as definitive or adjuvant therapy either as a boost or stand-alone therapy. High local control rates can be achieved in pts with positive margins with BT alone. LND is important to maintain high levels of regional control particularly in those receiving BT alone.